Truce takes hold in Ukraine as West mulls new Russia sanctions

Ukraine and pro-Kremlin rebels signed up to a truce Friday that could stem nearly five months of bloodshed but is unlikely to quell the separatist drive in the east.

Sceptical Western governments said they still planned to impose tough new sanctions on Moscow over what they see as clear Russian aggression against the former Soviet state.

US President Barack Obama said the new EU and US measures -- targeting Russia's defence, energy and financial sectors -- were needed to ensure "follow-through" on the ceasefire, but said they could be lifted if the truce holds.

The guns appeared to have fallen silent in eastern Ukraine after both sides ordered a halt to fire at 1500 GMT, despite fierce fighting around the strategic port city of Mariupol in the tense hours before the deal.

Western leaders remain wary, suspecting Russian President Vladimir Putin of trying to cement territorial gains in Ukraine that began with his March seizure of the Black Sea peninsula of Crimea.

And NATO approved a new "spearhead" force of several thousand soldiers at its summit on Friday, vowing to maintain a "continuous" presence in eastern Europe that could calm the nerves of ex-Soviet satellites that view Putin's intensions with dread.

The ceasefire plan was drawn up after a surge in tensions following NATO's accusations that Russia had sent in large numbers of heavily-armed troops to support a lightning rebel counter-offensive across the southeast that forced a dramatic reversal of fortunes for the Ukrainian army.

Under the terms of the truce outlined by the pan-European security body the OSCE, Kiev and the rebels agreed to pull back troops, swap their captives and send humanitarian aid to the stricken areas of eastern Ukraine.

"The fact that this ceasefire should last long is now our common responsibility," Ukraine's Western backed President Petro Poroshenko said.

But the deal could hand the rebels effective control of Ukraine's industrial heartland and leave Poroshenko exposed to charges of signing off on Kiev's surrender to Putin.

Ukrainian Prime Minister Arseniy Yatsenyuk said the deal required US and EU backing because Kiev could "not manage with Russia on our own".

"The peace plan must include a ceasefire, the withdrawal of the Russian army, bandits and terrorists, and the re-establishment of the border," he said.

Rasmussen, who has been strongly critical of Russia's role in Ukraine, said the next "crucial step is to implement it in good faith".

"But so far, so good," he added. "(This) could be the start of a constructive political process."

The US Department of Defence had warned Thursday that the 20,000 Russian troops it suspects are massed on the Ukrainian border were "more lethal" than ever before.

But the Kremlin accuses NATO and Washington of concocting evidence about what some have labelled an invasion by stealth in order to expand its own presence along Russia's western frontier.

Putin's spokesman told Russian news agencies he expected the ceasefire to be "thoroughly implemented" and that all sides would continue talks to reach a "full settlement of the Ukraine crisis".

- East's status uncertain -

Poroshenko said he was "satisfied" with the deal, which could see detained fighters on both sides freed on Saturday.

AFP journalists said the situation was now calm around Mariupol and in the main rebel bastion of Donetsk, one of the key battlegrounds in the conflict.

Yet the pact has done little to calm the separatist passions of insurgents who first overran government buildings across the Russified east in April, deeply mistrustful of the nationalist-leaning government that took power in February after the ouster of a Kremlin-backed leader.

The subsequent fighting has killed nearly 2,800 people and sent at least half a million fleeing their homes, wreaking devastation across towns and cities and leaving many residents short of water, food and power.

"(The) ceasefire does not mean a change in our goal to split from Ukraine," rebel representative Igor Plotnitsky told reporters in Minsk.

The peace plan -- first detailed by Putin after telephone talks with Poroshenko earlier this week -- could actually leave the rebels in effective control of a region that accounts for one-sixth of Ukraine's population and a quarter of its exports.

There are also doubts about whether the loose band of rebel field commanders will listen to political leaders such as the self-declared "prime ministers" of Lugansk and Donetsk who approved the pact.

A unilateral truce Poroshenko declared in June was initially backed by the rebels' political leadership and endorsed by Moscow. But it collapsed 10 days later because of unceasing militia attacks.

And OSCE officials said Friday that the crucial issue of the future status of the self-proclaimed rebel entities in Donetsk and Lugansk were not discussed in Minsk.

And Donetsk resident Viktor Kosobokov, 72, bluntly told AFP as he swept the streets that he was opposed to a deal with Kiev.

"We cannot talk to this government which has destroyed half of the Donbass," he said, referring to the eastern region.

"We must advance onwards to Kiev so they live through what we have had to endure."